Apparatus for driving and extracting stakes

ABSTRACT

A hand-held tool having a motor, a vibration mechanism, and a stake-gripping device is disclosed for driving and extracting stakes or posts. The vibration mechanism generally comprises a housing surrounding a pair of geared eccentric plates or geared weighted plates that are rotated by the motor. The stake-gripping device is attached to the vibration mechanism so that vibrations are transferred into a stake or post through the device housing. Internally, the stake-gripping device comprises a pair of toothed plates with at least one of the plates mounted to the housing utilizing springs. The spring mounted plate has an attached wire connected to a handle. As the handle is grasped, the wire pulls the stake-gripping device into the open position allowing placement of a stake or post into the device. When the handle is released, the toothed plate squeezes the stake or post inside the housing.

CROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part and claims the benefit of U.S. Patent applicationSer. No. 10/997,263 filed on Nov. 26, 2004. FIELD OF THE INVENTION

The present invention relates to a vibratory hand-held tool formechanically driving and extracting a stake or post into and out of theground or other support surface.

BACKGROUND OF THE INVENTION

Driving stakes or posts into the ground is required in manycircumstances related to the building of foundations, fences, and otherapplications. The physical act of driving such stakes or posts istypically labor intensive and performed manually by a worker using ahammer or maul. In many circumstances, the numbers of stakes or poststhat must be driven into the ground are such that manual placement ofthe stakes or posts is cost prohibitive and a mechanical means ofperforming the job is necessary to speed the process. In addition, thework site in which the stakes or posts must be driven may be remote ormay not have an adequate power supply, thus the mechanical stake/postdriver

must be relatively lightweight and self-powered. In response to theseconcerns, others have disclosed mechanical stake/post drivers. U.S. Pat.No. 6,347,672 discloses a hammer element configured to strike a stake orpost. The hammer element is coupled to a handheld jackhammer via aspindle. The hammer element is housed within a guide assembly thatcomprises a lower portion to receive the stake/post and an upper portionto receive the spindle.

U.S. Pat. No. 5,806,608 discloses an air-driven post driver thatincludes a hammer assembly and post receiving assembly. The hammerassembly includes an air-driven piston hammer disposed within a cylinderbore of a cylinder body having an upward thrusting air passageway, whichincludes a radially oriented upward intake passageway and alongitudinally oriented upward discharge passageway, and a downwardthrusting air passageway, which includes a radially oriented downwardintake passageway and a longitudinally oriented downward dischargepassageway having a threaded downward discharge port.

U.S. Pat. No. 5,667,021 discloses a stake driver including a frame forsupporting a hammer and a stake under the hammer. The hammer is securedupon movable mounts and is raised via a hoist and repeatedly dropped toeffect the driving of the stake.

U.S. Pat. No. 5,494,117 discloses a metal fence post driving apparatusformed by a platform rearwardly supported by the three point hitch of aconventional tractor and having a fluid pressure generating unit on theplatform driven by the tractor power takeoff. A mast having a top endportion rotatable about its vertical axis pivotally supports a boomintermediate its ends for horizontal and vertical pivoting movement ofits respective end portions by a first fluid pressure operated cylinder.A second fluid pressure cylinder pays out and retracts one end portionof the wire line of a block and tackle unit for elevating and lowering afluid pressure operated reciprocating unit axially disposed on a posttop to be driven into the ground.

U.S. Pat. No. 5,107,935 discloses an accessory for a jackhammercomprising a clamping means for gripping the upper end of the stake sothat the user can controllably drive the stake into the ground. Theaccessory includes a stake receiver that has a channel into which theend portion of the stake is inserted and further includes a jaw andclamping means for forcibly retaining the jaw against the insertedstake. The channel includes guide ways that permit it to be usedinterchangeably with the more common sizes and shapes of stakes. U.S.Pat. No. 5,088,567 discloses a device having a plurality of guides and astriking mass movable by a hydraulic cylinder. The hydraulic cylinder isarranged with its longitudinal axis outside the path of the center ofgravity of the striking mass. The striking mass can comprise a firstelastomeric and/or plastic component and a second heavy metal component.Three guides, which can be parallel to the movement path of the centerof gravity, are provided for guidance of the striking mass, the strikingmass is preferably constructed to be guided at its respective areas.

U.S. Pat. No. 5,819,857 discloses a portable power driven post driverhaving an inner hollow cylinder open at its upper end and adapted toreceive a post through a locking mechanism located at its lower end. Theinner cylinder is located within an outer surface of the outer cylinder;the longitudinal axes of the two fluid powered cylinders being inalignment. A common piston rod extends between the two pistons and isattached by a fastening member to the inner cylinder, the fasteningmember extending through a slot in the outer cylinder. A valve receivescompressed fluid, such as compressed air, and cyclically and alternatelydirects the compressed fluid to the two fluid powered cylinders toalternately raise the outer cylinder above the inner cylinder and todrive the upper cylinder downwardly into post driving contact with theupper end of a post held by the inner cylinder.

U.S. Pat. No. 4,665,994 discloses a portable hand held post driver whichis fully operable by a single worker and which uses a fluid poweredcylinder to drive posts into the ground. The cylinder raises a balanceddriving weight and forces the weight down onto the post. The cylinder isreversed automatically at both the top and bottom of its stroke toautomatically repeat the driving strokes so long as the operator holds ahand lever. The post is clamped to the frame of the implement by a clamphaving an overcenter control linkage. Before the implement can beoperated, a safety-linking pin must be intentionally released byoperating a safety lever.

The common feature among all of these prior art devices is that eachapparatus employs a striking mass to hammer the stake or post into theground. However, in the area of pile driving, wherein the members beingdriven into the ground are much larger and requires significantly moreenergy, it has been found that when a pile is subjected to intenselinear vibration along the axis of the pile, and when the weight of thevibratory driving apparatus is added to the weight of the pile, the rateof penetration is more frequently found to be considerably faster thanwould be obtained using a hammer-type apparatus. Furthermore, byemploying vibratory forces rather than a hammer-type force, the samehandheld tool used to drive the stake or post into the ground could beused to remove the stake or post after it has been set in place.Hammer-type stake/post drivers are incapable of removing a stake or postfrom the ground.

U.S. Pat. No. 5,725,329 discloses a linear-type pile driver that issuspended above a pile via a crane. The driver comprises a lifting shaftisolated from but slideably mounted within a piston assembly which isattached to a frame assembly, a cylinder assembly attached a reactionmass, the piston assembly being vibratorily positioned within thecylinder assembly and vibratorily driven by hydraulic fluid at aselectable frequency thereby vibrating the piston/frame assembly.

U.S. Pat. No. 4,819,740 discloses a rotational-type pile driver that isalso suspended above a pile via a crane. The vibratory pile driverincludes, among other elements, a pair of eccentric weights mounted onshafts for rotation about an axis transversely of the clamped piling forimparting vibratory forces to the piling as the eccentrics are driven inrotation.

These examples of pile drivers, however, are designed for driving andextracting piles, which are typically large timbers or pipes, and cannotbe employed for the much smaller scale operation of driving stakes orposts. Thus, it is desirable to have a simple, lightweight, vibratorystake/post driving apparatus that could be used by an individual toefficiently set stakes or posts.

SUMMARY OF THE INVENTION

Accordingly, an apparatus for driving and extracting stakes is providedgenerally comprising a hand-held tool having a motor, a vibrationmechanism, and a stake-gripping device. The motor may be electric orgasoline powered. The disclosed vibration mechanism generally comprisesa housing surrounding a pair of geared eccentric plates or gearedweighted plates that are rotated by the motor via a motor gear. Thestake- gripping device has a housing having an opening at its lower endfor receiving a stake or post. The stake-gripping device is fixedlyattached to the vibration mechanism so that the vibratory energy createdby the vibration mechanism is transferred into a stake or post throughthe stake gripping device housing. In one preferred embodiment, thestake- gripping device internally comprises a pair of toothed platesthat are mounted on the internal surface of the housing. At least one ofthe toothed plates is mounted to the housing utilizing springs. Thespring mounted plate is installed with an attached wire connected to ahandle which acts similar to a throttle cable. As the handle is graspedthe wire pulls the stake-gripping device into the open position. Thisallows easy placement of a stake or post into the stake-gripping device.When the handle is released, the attached wire allows the toothed plateto squeeze the stake or post inside the stake-gripping device housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side perspective of one preferred embodiment of the presentinvention.

FIG. 2 is an overhead perspective of the preferred embodiment shown inFIG. 1.

FIG. 3 is an overhead perspective of the vibrating mechanism of onepreferred embodiment featuring geared eccentric plates.

FIG. 4 is an overhead perspective of the vibrating mechanism of anotherpreferred embodiment featuring geared weighted plates.

FIG. 5 is a side perspective of the vibrating mechanism of FIG. 4.

FIG. 6 is a side perspective of one preferred embodiment of thestake-gripping device.

PREFERRED EMBODIMENTS OF THE INVENTION

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings, which form a parthereof, and in which are shown by way of illustration specificembodiments in which the invention may be practiced. It is to beunderstood that other embodiments maybe utilized and structural changesmaybe made without departing from the scope of the present invention.

One preferred embodiment of the present invention is illustrated inFIG. 1. The stake driving and extracting apparatus 10 generallycomprises motor 20 placed in positioned such that the shaft (not shown)is aligned in a vertical direction. Motor 20 is shown as a gasolinepowered engine having a pull cord 5 to start the engine. While the sizeof motor 20 can be chosen for a given application, a 2-stroke 25-75cubic centimeter engine should suffice for most stake drivingapplications. A larger engine can be installed for large stakes and/orposts. Motor 20 could also be a standard squirrel cage induction motorpowered by an electrical source.

Shaft housing 15 is attached to the bottom end of motor 20. Housing 15serves to protect the shaft extending from motor 20 and also to supportthe weight of the motor 20. The shaft housing 15 can be manufactured ofany suitable lightweight material, such as hard plastic or aluminum, andis attached to motor 20 by bolts 25. The bottom end of shaft housing 15is attached to vibrating mechanism 30 via plate 35. Plate 35 is asubstantially flat plate having an opening for the passage of the shaftfrom motor 20. Bolts 55 are inserted through a lip on the bottom ofshaft housing 15 which secures housing 15 to plate 35 and connects shafthousing 15 to vibrating mechanism 30. Alternatively, plate 35 can beformed as an integral part of shaft housing 15.

Vibrating mechanism 30 is disposed above stake-gripping device 40, bothof which are described in more detail below. Vibrating mechanism 30 isattached to stake-gripping device 40 via bolts 45. After the motor 20,shaft housing 15, vibrating mechanism 30 and stake-gripping device 40are bolted together, the parts form a substantially rigid device.

In order to operate the disclosed apparatus, the motor 20, shaft housing15, vibrating mechanism 30 and stake-gripping device 40 are suspendedfrom frame 60. Frame 60 may be constructed of any suitable lightweightmaterial, such as hard plastic or aluminum. The upper portion of frame60 surrounds motor 20 and is connected to plate 35 by a pluralitysupport members 65. Frame 60 also includes a pair of opposing handles90. Handles 90 may be fitted with rubber grips. With this configuration,a user may grasp handles 90 and hold the entire apparatus as it issuspended from frame 60.

The embodiment illustrated in FIG. 1 also comprises a throttle 70 and agripping mechanism 75, each mounted upon a separate handle 90. Throttle70 is connected to motor controller 95 via a standard throttle cable 80.By squeezing throttle 70 against handle 90, the user can control thespeed of motor 20. Gripping mechanism 75, which is attached tostake-gripping device 40 via cable 85 operates in a similar fashion tothrottling cable 80. The user squeezes gripping mechanism 75 againsthandle 90 in order to insert a stake or post into stake-gripping device40. Once a stake or post is inserted, the user releases the grippingmechanism 75, which causes stake-gripping device 40 to internally securethe stake or post.

FIG. 2 shows the apparatus of FIG. 1 in an overhead perspective. Frame60 surrounds motor 20 and, as described above, is connected to plate 35(not shown) by a plurality of support members 65. Motor 20 includes afuel tank that is filled through port 22 and a motor controller 95.

Motor controller 95 contains the necessary components to start and stopmotor 20, such as an on/off switch 24, priming bubble 26, and a throttleattached to throttling cable 80. Motor 20 may also include a chokedevice and any other components that are installed on conventionalmotors used to operate hand-held power tools.

One preferred embodiment of vibrating mechanism 30 is illustrated inFIG. 3. The mechanism 30 is shown from an overhead perspective and withplate 35 removed. All of the internal components of vibrating mechanism30 are housed within housing 105. Housing 105, like the other componentsof the apparatus, may be constructed of any suitable lightweightmaterial, such as plastic or aluminum. Housing 105 attaches to shafthousing 15 (shown in FIG. 1) via bolts that engage bolt holes 110. Plate35 is positioned between housing 105 and shaft housing 15 as describedabove. Housing 105 may be reinforced by cross-member supports 155.

Inside housing 105, the shaft extending from motor 20 terminates withinshaft keyway 130, which forms a centralized opening within motor gear135. While FIG. 3 illustrates a keyway 130 having a cross shape, anyconventional method of connecting the shaft to motor gear 135 may beemployed. Motor gear 135 is disposed in a perpendicular arrangement withrespect to the shaft extending from motor 20 such that as motor 20 turnsthe shaft, the shaft turns motor gear 20. Also disposed within housing105 are two geared eccentric plates 140 that are mounted on opposingwalls of housing 105. The geared eccentric plates 140 have a gearedportion 145 and an eccentric plate portion 150. Geared portion 145 ismechanically coupled via gear teeth to motor gear 135. Thus, as motorgear 135 rotates in its plane (perpendicular to the shaft of motor 20),so do geared eccentric plates 140; however, geared eccentric plates 140rotate in a plane parallel to the shaft of motor 20. The eccentric plate150 portions of plates 140, because of their eccentricity, createvibrational energy as they turn. This is because of the imbalance of thecenter of mass of the geared eccentric plates 140 as the plates rotatedaround its central axis. As stated above, the geared eccentric plates140 are mounted on opposing internal walls of housing 105. In order tomaximize the amount of vibrational energy created as the eccentricplates rotate, it is preferred to mount plates 140 with each plate'scenter of mass 180 degrees apart when viewed along the axis of rotation.The vibrational energy is transferred from the mechanical apparatus andinto a stake or post that has been attached to the stake-grippingdevice.

Geared eccentric plates 140 are mounted onto the internal surface ofhousing 105 by sliding engagement upon shaft 160, which extends outwardfrom the internal wall of housing 105. Bushing 120 separates gearedeccentric plates 140 form the internal wall of housing 105 to ensurethat geared eccentric plates 140 are allowed to spin freely.

Another preferred embodiment of vibrating mechanism 30 is illustrated inFIG. 4. Again, the vibrating mechanism 30 is shown from an overheadperspective and with plate 35 removed. The primary difference betweenthe device shown in FIG. 4 as compared to the device shown in FIG. 3 isthe replacement of geared eccentric plates with geared weighted plates240. In addition, the motor gear 235, along with the shaft from motor20, has been shifted off center to make room for axle 260. Axle 260 isattached to opposing walls of housing 205 and offers more support forgeared weighted plates 240.

Geared weighted plates 240, like the geared eccentric plates, have ageared portion 245 that is mechanically coupled via gear teeth to motorgear 235. Plates 240 also have a weighted plate portion 250 that has aweight 255 attached near the outer edge of the weighted plate portion250. The weight moves the center of mass of the geared weighted plate240 away form the central axis of rotation such that as the weightedplate 240 rotates it creates vibrational energy. As with the embodimentshown if FIG. 3, the weighted plates 240 should be mounted on axle 260such that the center of mass of each plate is 180 degrees apart whenviewed along the axis of rotation in order to maximize vibrationalenergy.

Weighted plates 240 are mounted onto the internal surface of housing 205by sliding engagement upon axle 260, which extends from opposinginternal walls of housing 205. Bushing 220 separate weighted plates 140from the internal wall of housing 205 to ensure that geared weightedplates 240 are allowed to spin freely.

FIG. 5 is a side perspective of vibrating mechanism 30. Shaft 270 isshown extending down from motor 20 (not shown). Shaft 270 extends intothe keyway of motor gear 235 and rotates 5 the motor gear 235 as theshaft 270 rums. The teeth of motor gear 235 are mechanically engagedwith the teeth of the geared portion 245 of the geared weighted plates240. Thus, as motor gear 235 rotates, so do the geared weighted plates240. The weighted plates 240 are slidingly positioned onto axle 260which extends from opposing walls of housing 205. Bushings 220 ensurethat plates 240 are allowed to rotate freely.

FIG. 6 is a side perspective of one preferred stake-gripping device 40.The device comprises a housing 305 that attached to housing 205 of thevibrating mechanism 30 via bolts 345. The lower portion of housing 305has a square or rectangular cross-section and an opening 350 forinserting a stake or post. A pair of stake gripping plates 315 aremounted on opposing internal walls of housing 305. The gripping plateshave a toothed or serrated surface 325 to firmly grip a stake or post.The gripping plates are attached to the internal walls of housing 305with springs 320, which may be standard coil springs, torsion springs,or any other type of spring, to allow varying positions of grippingplates 315 to permit the insertion of stakes or posts with varyingdimensions. In one preferred embodiment, the housing 315 is ofsufficient size to accept a stake constructed of a standard 2×4 timber.

As shown in FIG. 6, at least one plate 315 is attached to a wire 385,which is coupled to the handle 75 on frame 60 (shown in FIG. 1). Thewire operates similar to a standard throttling cable, such that when thehandle 75 is depressed, the wire pulls plate 315 and compresses springs320. This arrangement allows the gripping plates 315 to be opened forinsertion of a stake or post. Alternatively, both gripping plates 315can be attached to the internal wall of housing 305 along with a wire385, which are both routed to handle 75 on frame 60.

Alternatively, gripping plates 315 may be operated by a hydraulicmechanism that is controlled by handle 75 on frame 60, or by anymechanical linkage know in the art that may be remotely operated via thehandle 75 on frame 60.

Gripping plates 315 are shown as planar members in FIG. 6.Alternatively, gripping plates 315 may be shaped to accept stakes andposts of various shapes, such as an arcuate shape for accepting roundposts. For example, plates having a concave gripping surface forming asemi-cylindrical space may be employed when driving and extractingstakes or posts having a circular cross-section.

Although the present invention has been described in terms of specificembodiments, it is anticipated that alterations and modificationsthereof will no doubt become apparent to those skilled in the art. It istherefore intended that the following claims be interpreted as coveringall alterations and modifications that fall within the true spirit andscope of the invention.

1. A hand-held vibratory apparatus for driving and extracting a stake, the apparatus comprising: a motor having a shaft; a vibrational energy generating means coupled to the shaft and powered by the motor; a stake-holding means connected to the vibrational energy generating means such that vibrational energy generated by the vibrational energy generating means is transferred to a stake through the stake-holding means, wherein the stake-holding means further comprises a gripping device enclosed within a housing, the housing having an opening at bottom end for the insertion of a stake, the gripping device comprising at least one member coupled to the housing and capable of being movingly positioned in order to grip the stake; and a frame assembly from which the motor, the vibrational energy generating means, and the stake-holding means are suspended, the frame assembly having a pair of handles for holding and operating the hand-held vibratory apparatus.
 2. The apparatus of claim 1, wherein the gripping device is remotely controlled via a control mechanism mounted upon at least one of the handles of the frame assembly.
 3. The apparatus of claim 1, wherein the gripping device is hydraulically actuated.
 4. The apparatus of claim 1, wherein the gripping device is mechanically actuated.
 5. The apparatus of claim 1, wherein the vibrational energy generating means comprises a vibration mechanism enclosed within a housing, the vibration mechanism comprising a motor gear coupled to the shaft, a plurality of plates wherein the plates have a center of mass away from the plates' axis of rotation, the plurality of plates having a gear teeth portion mechanically engaging the motor gear such that as the motor gear rotates so do the plurality of plates, the plurality of plates mechanically coupled to the housing such that the plurality of plates are allowed to spin freely as the motor gear turns.
 6. The apparatus of claim 5, wherein the plurality of plates further comprises an eccentric portion connected to the gear teeth portion, such that the eccentric portion moves the center of mass of the plate away from the axis of rotation.
 7. The apparatus of claim 5, wherein the plurality of plates further comprises a concentric portion connected to the gear teeth portion and a weighted member connected to the concentric portion, such that the weighted member moves the center of mass of the plate away from the axis of rotation.
 8. The apparatus of claim 1, wherein the surface of the at least one member for gripping a stake has a roughed surface to increase friction and improve grip on a stake.
 9. The apparatus of claim 8, wherein the surface of the planar member contacting the stake has a plurality of teeth to grip a stake.
 10. The apparatus of claim 1, wherein the surface of the at least one member is planar.
 11. The apparatus of claim 1, wherein the at least one member has an arcuate surface.
 12. The apparatus of claim 1, wherein the frame assembly comprises an upper section surrounding and protecting the motor and a lower section comprising a plurality of support members, the support members connecting the upper section of the frame assembly to the vibrational energy generating means.
 13. The apparatus of claim 15, wherein the handles of the frame assembly further comprise controls for throttling the motor and actuating the stake holding means.
 14. The apparatus of claim 16, wherein the vibrational energy generating means comprises a vibration mechanism enclosed within a housing, the vibration mechanism comprising a motor gear coupled to the shaft, a plurality of plates wherein the plates have a center of mass away from the plates' axis of rotation, the plurality of plates having a gear teeth portion mechanically engaging the motor gear such that as the motor gear rotates so do the plurality of plates, the plurality of plates mechanically coupled to the housing such that the plurality of plates are allowed to spin freely as the motor gear turns.
 15. The apparatus of claim 17, wherein the plurality of plates further comprises an eccentric portion connected to the gear teeth portion, such that the eccentric portion moves the center of mass of the plate away from the axis of rotation.
 16. The apparatus of claim 17, wherein the plurality of plates further comprises a concentric portion connected to the gear teeth portion and a weighted member connected to the concentric portion, such that the weighted member moves the center of mass of the plate away from the axis of rotation. 